Exploding stars and other
violent cosmic events are
thought to flood the uni
verse with gravity waves.
Rippling through space
time at the speed of light,
they briefly disturb every
thing in their path. Too
weak to detect so far, these
waves create distortions
smaller than the diameter
of a single particle inside
an atomic nucleus.
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PAINTINGBY NATIONALGEOGRAPHIC
ARTISTWILLIAMH. BOND
r4
Within earth's gravitational
E
field (D) you feel the effect
of gravity by just standing
still on a fixed surface (F).
To experience weightless
ness, you would have to free
fall like a skydiver, who feels
only air resistance (E).
With this equivalence
principleand his general
ized theory, Einstein trans
formed our understanding
of the universe and its ori
gins. Yet his theory has not
been integratedwith quan
tum mechanics, the math
ematical languagefor
theories of the.other funda
mental forces of nature, and
Einstein died searchingfor a
still elusive unified theory.